Process for the preparation of threads from cellulose acetate



Patented May 4, 1926.

UNITED STATES I I 1,583,711 PATENT OFFICE.

EMIL EUEEET, oTTo LEUCHS, AND runwio LOCK, or ELBERFELD, GERMANY, Assronons To FARBENFABRIKEN vonM. FRIEDR. BAYER AND co., or LEVER- xUsEu, NEAR COLOGNE-ON-THE-RHINE, GERMANY.

rEooEss FOR TH PEEPAEATIoN or THREADS FROM CELLULOSE AoETATE.

No Drawing. Application filed July 14,

To all whom it may concern:

Be it known that we, EMIL HUnnnT, O'r'ro LEUCHS, and LUDWIG Loon, citizens of Germany, residing at Elberfeld, in the State of Prussia, Germany,'have invented new and useful Improvements in aProcess for the Preparation of-T-hreads from Cellulose Acetate, of which the following is a specification.

In German Patent No. 274,260 a process is described, according to which a solution of acidyl cellulose is formed into threads by spinning into a highly concentrated salt solution. The fineness of the threads obtained according to this process depends principally on the diameter of the jet and .on the content of solid substance in the spinning solution, as the formed thread is completely coagulated very soon after leaving the 'jet and ceases to be extensible any longer. Thus, for instance, in order to obtain threads of an average capillary value of 7-8 deniers, it is necessary to vork with very fine jets; in the most favora le case a jet diameter of 0.2 mm. will be p0 ible. With larger jet apertures, e.g. 0.4-1.0 m., merely artificial horse-hair can be pro uced. In regard to the extraordinarily high viscosity of the spinning solutions of acidyl c lluloses, this circumstance implies very tro blesome manufacturing. difliculties amon t other things, it becomes necessary to work with very high pressures.

The noteworthy observation has nowbeen made, according to which stretching spinning may be carried out in-such a way that threads of a fineness of 3 deniers and less may be obtained from jets of about 0.6 mm. diameter, by' using instead of a single sol-' vent mixtures of the same. I

- To a solution of cellulose acetate in acetone, which is to be spun into a bath of concentrated calcium chloride solution, may be added for example benzene-alcohol, benzene-chlorobenzene, ethyl acetate, pyridine, chloro-alcohol, aniline etc. in quantities from 5-20 per cent. To an acetic acid solution which is to be precipated with a concentrated solution of sodium acetate, may be added for example, chloroalcohol, acetylene'tetrachloride etc. Very small quan tities'of these additions are sulficient for w I producing the desired efiect.

As regards the choice of the substance to 1924. Serial No. 725,980.

be added, it is an important consideration that the substance in question must be more difficultly extracted by the spinning bath, in consequence of which the coagulation of the thread is retarded. Moreo-verthe addition must be adjusted according to the nature, concentration, and temperature of the spinning bath and to the length of immers on in the bath. Spinning may also. be carfled-01113, so that only a part of the solvent mixture passes into the'spinning bath, while the remainder evaporates on passing through the air. By this means special efi ects are produced in respect to lustre, strength and aflinity for dyeing. According to these directions it becomes merely a matter of trial, to find the best addition and the most suitable conditions for spinning.

The use of mixtures of solvents and precipitants or non solvents is described in 'French Patent No. 426,436, for example, the 'addition of alcohol, carbon tetrachloride,

is obtained contrary to the direction of the French specification. by adding the nonsolventto the spinning solution only in small quantities.

In order to illustrate the new process more fully the following examples are given Example ..4 parts by weight of pyridine are added to 20 parts by'weight of cellulose acetate dissolved in 78 parts by weight of acetone. Spinningvat a temperature of 45 with a speed of spinning of 40 metres and usin a spinning bath containing 23 per cent of I 261,. A capillary thread of 13 p. di-

diameter are employed using a pressure of A; atmosphere.

Ewample .2.20 parts by weight of cellulose acetate are dissolved in 75 parts by ameter corresponding to a titer of less than 3 deniers is obtained when jets of 0.7 mm.

weight of acetone and 5 parts by weight of I chlorobenzene' are added. The solution thus obtained is spun into a calcium chloride bath of 23 per cent strength at a temperature of 42. The calcium chloride spinning bath contains about 5 per cent of acetone calculated on the amount of calcium chloride solution. \Vith a jet of 0.6 111111; diameter and employing a pressure of 1.2 atmospheres and .a speed of spinning of 35 metres a monofil' thread is obtained of a titer of 2.7 deniers.

We claim 1. Process for'the preparation of threads of cellulose acetate which comprises spinning a solution of cellulose acetate into a strong salt solution, said solution of cellulose acetate consisting of cellulose actate and a single solvent therefor and oneor more materials different from said solvent which are absorbed by the salt solution more diflicultly than said solvent.

2. Process for the preparation of threads from cellulose acetate Whichcomprises spinning a solution of cellulose acetate into a strong salt solution, said solution of cellulose acetate consisting of cellulose acetate and a single solvent therefor and pyridine,

which is absorbed by the strong salt solution more diificultly than said solvent.

3. Process for the preparation of threads from cellulose acetate which comprises spin- 111 mg a solution of cellulose acetate in acetone into a strong calcium chloride solution, said 1 hands.

' EMIL HUBERT. OTTO LEUCHS. LUDWIG LOCK. 

